The present invention relates to an electrical connector for connecting electrical cable conductors, and more particularly to an electrical connector having insulation-piercing elements for use with an insulated electrical cable conductor.
Electrical connectors are often used for connecting cable conductors together. For example, an electrical connector may be used as a branch connector when electrical power is distributed from a power generation plant to consumers of electrical power. The electrical connector may have one or more openings for receiving an electrical cable conductor (“cable”). A cable is typically round in cross-section and formed of a conductive core (typically copper or aluminum) and may be surrounded by one or more layers of insulating material (“insulative coating”). Additionally, multiconductor cable constructions containing sector shape (i.e., a pie shape) insulated conductors with an overall outer sheath are used in some countries. An electrical connector may be an insulation-piercing connector (“IPC”), which incorporates insulation-piercing elements in the cable-receiving opening in order to create an electrical connection between the electrical connector and the insulated cable. The IPC may include a fixed jaw and a movable jaw, where the movable jaw creates an opposing force on a cable which is engaged between the fixed jaw and the moveable jaw. The movable jaw may be actuated by a threaded bolt extending through a threaded bore in the electrical connector body. A cable may be inserted between the jaws, and as the bolt is turned, the movable jaw moves toward the fixed jaw and engages the cable. An IPC may also be formed by a bolt and a fixed jaw, where the bolt creates an opposing force on the engaged cable.
Where an IPC has two opposing jaws, insulation-piercing elements (e.g., teeth) are typically formed on each jaw in order to pierce an insulative covering of the cable and make electrical contact with the conductive cover of the cable as the movable jaw is clamped down on the cable. The teeth may be essentially two-dimensional or fully three-dimensional. In order to cover a range of cable sizes, it may be preferred to arrange the teeth with their initial cable contacting surfaces in an arced profile on each jaw, so that the teeth contact as much of the cable perimeter as possible for low contact resistance. In current IPC designs, where a fixed jaw and moveable jaw configuration is used, the opposing sets of teeth are typically mirror images of one another.
An IPC may also be used in other applications that require creating an electrical connection through an insulated cable. An IPC may be used because of shorter cable installation time due to little or no cable preparation (e.g., there is no need to strip insulation from a cable in order to establish electrical contact). The design of an IPC requires a balance between several different criteria, including, but not limited to, a low penetration force through the insulative layer of the cable, the ability to penetrate and displace the insulation, low total installation force (or torque), low damage to the cable, low contact resistance, low overall Joule heating, good long term electrical connection stability, and a sufficient grip on the cable (“strain relief”) to prevent cable movement and dislodgment from the connection.
It may also be desirable for an IPC to be “range-taking”. That is, it may be desirable to have an IPC that has the ability to connect reliably to a wide range of cable sizes (e.g., different cable diameters). It has been found that a broad range-taking capability may be difficult to achieve with current IPC designs because when the teeth on opposed jaws in an IPC are closed down onto a small diameter cable, some of the teeth may crash into each other, preventing the proper force from being applied to the cable.